Tire sidewall

ABSTRACT

A new class of antiozonant compounds, namely tris(N-alkyl-p-phenylenediamino)-1,3,5-triazine compounds, are incorporated into thermosetting compositions having at least one highly unsaturated rubbery polymer and at least one other elastomer having lesser unsaturation, such as EPDM. Thermosetting compositions are most useful as tire sidewall compositions which may be preferably cured with blends of organic peroxide and sulfur donor accelerators.

CROSS-REFERENCE TO RELATED APPLICATION

This is a division of application Ser. No. 07/163,921 filed Mar. 4,1988,now U.S. Pat. No. 4,946,881 which is a continuation-in-part ofapplication Ser. No. 90,298 filed Aug. 28, 1987, now U.S. Pat. No.4,794,135.

BACKGROUND OF THE INVENTION

This invention relates to the use of new triazine as antiozonants forthermosetting rubber compositions and their preferred use as sidewallcomponents in tires. More particularly, their use in blends of highlyunsaturated rubbers and rubbers with lesser unsaturation, such as EPDM.

It is well known that ozone causes surface cracking of conventionalhighly unsaturated rubber vulcanizates used in tires when the rubber isplaced under strain in an ozone environment. The most severedeterioration occurs when a small number of cracks are formed which growrapidly into deep, disruptive fissures. These ozone cracks seriouslyshorten the serviceable life of the tire, especially in the area of thesidewall.

Conventional chemical antiozonants have been developed which retard theformation of the ozone cracks occurring under static and dynamicconditions. Examples of antiozonants in common use include:N-phenyl-N'-(1,3-dimethylbutyl)-p-phenylenediamine;N-phenyl-N'-isopropyl-p-phenylenediamine;N-phenyl-N'-(1,4-dimethylpentyl)-p-phenylenediamine;N-phenyl-N'-(1-methylheptyl)-p-phenylenediamine;N-phenyl-N'-cyclohexyl-p-phenylenediamine; mixeddiaryl-p-phenylenediamines; N,N'-diphenyl-p-phenylenediamine;N,N'-di-beta-naphthyl-p-phenylenediamine;N,N'-bis(1,4-dimethylpentyl)-p-phenylenediamine;N,N'-bis(1-ethyl-3-methylpentyl)-p-phenylenediamine;N,N'-bis(1-methylheptyl)- p-phenylenediamine;N-phenyl-N'-p-toluenesulfonyl- p-phenylenediamine and blends of thesematerials.

The use of these well known paraphenylenediamine materials has improvedozone protection under both static and dynamic conditions, however, eventhe best of the class just described have a very strong tendency to bothstain and discolor. The term "stain" or "staining" is herein used todescribe the characteristic of a material to diffuse through a polymericsubstrate and discolor the adjacent surface. This diffusion staining ishighly objectionable in most light colored rubber articles. In tires,which is the largest application in which the ozone protection isrequired, the tendency to diffusion staining of the aforementionedparaphenylenediamine materials is objectionable particularly in whitesidewall type tires. Even in non-white sidewall type tires, the tendencyof the materials to diffuse to the surface of the tire sidewall can beobjectionable in that a brown, dull surface is created on the tiresidewall. This is aesthetically objectionable in that it detracts fromthe general jet black, smooth appearance of a new tire. It is obviousthat in a white sidewall tire, the migration of the brown discoloringmaterial to the surface of the white sidewall is highly objectionableand generally difficult to remove during cleaning of the tire surface.

Rubbers with lesser unsaturation have been blended with the highlyunsaturated diene based rubber to protect against ozone as disclosed inU.S. Pat. Nos. 3,630,974; 3,706,819; 3,830,274; 3,915,907; 3,937,862 and4,224,196. These have resulted in improved ozone resistance but reducedother desirable properties, such as adhesion, flex fatigue and others.

An object of this invention is to provide an antiozonant material whichis highly effective in protecting the carcass from ozone attack. Afurther object is to provide ozone protection to an EPDM/diene-typerubber blend and to improve flex fatigue of the tire into which thisblend is incorporated. Yet another object is to produce an ozoneprotection which slowly diffuses and does not produce an objectionablebrown bloom on a black or white sidewall.

The novel arylenediamine substituted triazine compounds of the inventionhave provided exceptional long term ozone protection under staticconditions without using wax. An advantage of the substituted triazinecompounds is that it produces a substantially non-staining antiozonantof high molecular weight. A further advantage is that it slowly bloomsto the surface of the rubber article. A further advantage is that thetriazine compounds of the invention provide outstanding dynamicprotection without the use of waxes preferably by blending said triazinecompounds with other known antiozonants and antioxidants. Anotheradvantage is that the compounds do not tend to increase scorchiness ofthe compounded rubber stock in which it is used. This improvesprocessing safety over other paraphenylenediamine antiozonants.

BRIEF DESCRIPTION OF THE INVENTION

The object and advantages of the invention may be obtained using theessential ingredient of the invention which is a compound of the generalformula: ##STR1## in which R¹, R² and R³ are radicals independentlyselected from a C₃ -C₁₈ branched or linear alkyl, or a C₃ -C₁₂cycloalkyl or a C₃ -C₁₂ cycloalkyl substituted with one or more C₁ -C₁₂alkyl groups. The compound of structure (I) is incorporated into athermosetting composition or a tire comprising at least one highlyunsaturated rubbery polymer and at least one other elastomer havinglesser unsaturation, such as an EPDM, EPR or butyl rubber, Thecomposition may be sulfur cured or preferably cured using a blend of anorganic peroxide with sulfur or a sulfur donor accelerator.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to structure (I), the preferred compositions are those inwhich R¹, R² and R³ are linear or branched C₃ -C₁₈ alkyl groups. Thealkyl groups more preferred are those with a secondary carbon in thealpha position to the nitrogen. In this configuration, the antiozonantactivity of the compound is believed to be enhanced. Therefore, the morepreferred alkyl groups are branched chains which provide an alkylsubstituent which is in accordance with this configuration. Thecycloalkyl or C₁ -C₁₂ alkyl substituted cycloalkyls provide such a alphacarbon configuration as well. The structure of formula I which is mostpreferred at this time are compounds in which R¹, R² and R³ are C₆ -C₈branched chain alkyl groups. Examples of some preferred chemicals of thepresent invention are:2,4,6-tris(N-1,4-dimethylpentyl-p-phenylenediamino)-1,3,-5-triazine:2,4,6-tris(N-isopropyl-p-phenylenediamino)-1,3,5-triazine;2,4,6-tris(N-cyclohexyl-p-phenylenediamino)-1,3,5-triazine;2,4,6-tris(N-sec-butyl-p-phenylenediamino)-1,3,5-triazine;2,4,6-tris(N-1,3-dimethylbutyl-p-phenylenediamino)-1,3,5-triazine;2,4,6-tris (N-1-methylheptyl-p-phenylenediamino)-l,3,5-triazine;2,4,6-tris(N-2,4-di-tert-butylcyclohexyl-p-phenylenediamino)-1,3,5-triazine;2,4,6-tris(N-2-sec-butylcyclohexyl-p-phenylenediamino)-1,3,5-triazine,2,4,6-tris(1-methyldecyl-p-phenylenediamino)-1,3,5-triazine. The mostpreferred material2,4,6-tris(N-1,4-dimethylpentyl-p-phenylenediamino)-1,3,5-triazine.

The compounds of the invention are most advantageously utilized asantiozonants to protect blends of highly unsaturated polymers such asnatural or synthetic elastomers and polymers of lesser unsaturation,such as EPDM or butyl rubber. Representative of the highly unsaturatedpolymers which may be employed in the practice of this invention arediene elastomers. Such elastomers will typically possess an iodinenumber of between about 100 and about 400, although highly unsaturatedrubbers having a higher or a lower (i.e., of 50-100) iodine number mayalso be employed. Illustrative of the diene elastomers which may beutilized are polymers based on conjugated dienes such as 1,3-butadiene;2-methyl-1,3-butadiene; 1,3-pentadiene; 2 chloro-1,3 butadiene,2,3-dimethyl-1,3-butadiene; and the like, as well as copolymers of suchconjugated dienes with monomers such as styrene, alpha-methylstyrene,acrylonitrile, methacrylonitrile, methyl acrylate, ethyl acrylate,methyl methacrylate, ethyl methacrylate, vinyl acetate and the like.Solution polymerized butadiene styrene copolymers and polypentenamers ofthe type derived from ring opening polymerization of cyclopentenematerials, alternately known as transpolypentene, may also be founduseful. Preferred highly unsaturated rubbers include natural rubber,cis-polyisoprene, polybutadiene, poly(styrenebutadiene), polychloropreneand poly(acrylonitrilebutadiene). Moreover, mixtures of two or morehighly unsaturated rubbers may be employed. Mixtures of the highlyunsaturated rubbers with elastomers having lesser unsaturation such asEPDM (ethylene-propylenediene rubber), EPR (ethylene propylene rubber),butyl or halogenated butyl rubbers are most preferred in this invention.These lesser unsaturation elastomers or rubbers have iodine numbersbelow 100 and preferably between 10 and 100, more preferably between 10and 50. Typical EPDM polymers have iodine numbers between 20 and 40.

U.S. Pat. No. 3,706,819 broadly discloses the use of EPDM terpolymerswith other highly unsaturated rubbers where the EPDM has anethylene/propylene ratio range of 80/20 to 20/80 and a non-conjugateddiene content of 2-20 weight percent.

U.S. Pat. No. 4,645,793 (Von Hellems et al) discloses particularlypreferred high molecular weight EPDM polymers of this high molecularweight class that have an ethylene:propylene weight ratio of about 50:50to about 75:25, preferably from 60-40 to about 75:25 and at least about6 and preferably at least about 7.5, most preferably at least about 9and up to about 15 weight percent bound non-conjugated diene based onthe total EPDM. Suitable such non-conjugated dienes include straightchain and cyclic dienes such as 1,4-hexadiene, ethylidene norbornene,norbornadiene, methylene norbornene, dicyclopentadiene, 2-methylnorbornadiene, 5-vinyl 2 norbornene and the like. Especially preferredamong such dienes is ethylidene norbornene. Preferably, the EPDM has anon-conjugated diene content of 7.5-15 weight percent. Methods forproduction of such EPDM polymers are well documented in the art.Preferably the amount of EPDM polymer in the elastomeric composition isfrom 15 to about 50 parts by weight per 100 parts by weight of totalelastomers.

For ease and efficiency of mixing the polymers, the high molecularweight EPDM polymer is provided as an oil extended polymer prior tomixing with the other polymers. The EPDM may be oil extended by thewell-known procedures of oil extending polymers by adding oil to thepolymer solution from the polymerization reactors and recovering the oilextended polymer; the oil is selected from aromatic, naphthenic orparaffinic oils, in amounts from about 50 to about 150 parts by weightof oil per 100 parts by weight of EPDM polymer. Alternatively, the oilcan all be separately added to the high molecular weight EPDM polymerduring the process of compounding the polymers.

Another EPDM polymer considered useful in this invention is disclosed inU.S. Pat. No. 3,915,907 (Hopper) in which a modified rubbery terpolymeris provided which comprises an admixture of a rubber terpolymer ofethylene, alpha-olefin containing 3-6 carbon atoms and a non-conjugateddiene containing 6-12 carbon atoms with an N-chlorothio-sulfonamide ofthe formula ##STR2## where the mole ratio of saidN-chlorothio-sulfonamide to unsaturated sites in said terpolymer is inthe range of about 0.06:1 to 1:1, where R' and R² are selected from thegroup consisting of alkyl radicals having 1-20 carbon atoms, aralkylradicals having 7-20 carbon atoms, alkaryl radicals having from 7-20carbon atoms, and haloaryl radicals having 6-10 carbon atoms and whereR" is also selected from radicals having the formula ##STR3## where R³and R⁴ are individually selected from said alkyl, aralkyl and haloarylradicals where R³ and R⁴ can be joined together to represent radicalsselected from --CH₂ --, where n is an integer of 4-7, and --(CH₂)₂--0--(CH₂)--.

Blends of highly unsaturated rubber with both EPDM and halobutyl rubbersare also considered useful in this invention. Such blends are known asnoted below but the results may be surprisingly enhanced by the additionof triazine compound (I) of the invention.

U.S. Pat. No. 3,630,974 (Ladocsi et al) discloses a composition whichprovides a vulcanizate with good dynamic ozone resistance and heat-flexresistance, provided by compounding an amount of halobutyl rubber, i.e.25-30 weight percent, with high unsaturation rubber and a terpolymercomprised of ethylene, lower 1-alkene and non-conjugated diene, i.e. anEPDM. The EPDM polymer used in the compositions of Ladosci et alcomprise 20-80 percent by weight ethylene, 75-15 percent by weight of C₂-C₁₀ alkene (normally propylene) and no more than 20 percent by weightof the diene, most preferably 0.1-6 mole percent. In the sidewallcompositions as a whole, the EPDM polymer represents 15-30 percent byweight.

U.S. Pat. No. 3,830,274 (Waser) discloses an elastomer blend and apneumatic tire sidewall prepared therefrom which comprise 20-60 percentweight percent of either natural or synthetic cis-1,4-polyisoprenecompounded with 20-35 weight percent of EPDM polymer and with from 20-45weight percent of bromobutyl rubber having specific characteristics. TheEPDM component of the invention is defined in preferred terms as havingthe following constitution: ethylene to propylene ratio of 50:50 to75:25 based on weight and from 2-20 weight percent units ofnon-conjugated diene.

In U.S. Pat. No. 4,224,196 (Gursky) there is disclosed a pneumatic tiresidewall composition which comprises a halobutyl rubber, a highunsaturation rubber and an oil extended EPDM polymer. The EPDM polymercomponent of the disclosed composition is described as comprising ultrahigh molecular weight polymers which have prior to oil extension aMooney viscosity in excess of about 100 at 260° F., an ethylene contentof between 50 and 75 percent and a diene level of from 3 percent to 12percent. Napthenic and paraffinic oils, in amounts from 25-150 parts byweight per hundred parts by weight of polymer, are used for EPDM oilextension.

The tire, in accordance with the invention whose sidewalls are formed atleast on the outer surface, of one or more blends of elastomers of thediene type and of the ethylene-propylene type is characterized by thefact that the portions of the sidewalls formed of the said blends arevulcanized by means of an organic peroxide and sulfur and/or sulfurdonor type accelerators.

The ethylene-propylene elastomer which is of preferred use is anethylene-propylene-diene terpolymer containing a small portion of adiene selected generally from among ethylidene norbornene,hexadiene-1,4, or, more exceptionally, from among methylene norbornene,dicyclopentadiene and cyclo-octadiene-1,5. It is particularly surprisingthat it is advantageous to covulcanize with peroxides anethylene-propylene-diene terpolymer into which a diene has beenintroduced to facilitate a sulfur vulcanization.

The amount of elastomer of the ethylene-propylene type to be used isbetween about 15 percent and about 60 percent by weight of the totalelastomers, the balance being formed of ordinary highly unsaturateddiene-based elastomers. A smaller amount--about 20 percent to about 40percent by weight constitutes the preferable range--can be used with aterpolymer having a high content of macromolecules of high molecularweight, that is to say a terpolymer having a Mooney plasticity ML (1+8')of more than about 100 at 100° C. for the non-oil extended base polymer.The best proportion is between about 30 percent and about 45 percent byweight for an ordinary terpolymer containing a relatively large numberof macromolecules of relatively low molecular weight, that is to say,having a Mooney plasticity of between about 50 and about 100 at 100° C.The use of an ethylene-propylene copolymer is believed to require ahigher proportion for the same effectiveness. However, one maybe able touse such a copolymer possibly mixed with a terpolymer to good advantage.

The curative system employed when blends of highly unsaturated andlesser unsaturation rubbers are utilized is critical to good physicalproperties. Any conventional sulfur cure system may be employed. Apreferred system comprises a sulfur containing cure component selectedfrom sulfur or a sulfur donor compound, at least one sulfur cureaccelerator and at least one organic peroxide curative.

The sulfur donor compounds which may be employed in conjunction with orin the alternative to sulfur are well known to those skilled in the artof rubber compounding. Illustrative of such sulfur donor compounds are2-(4-morpholinyldithio)benzothiazole, tetramethylthiuram disulfide,tetraethylthiuram disulfide, dipentamethylene thiuram hexasulfide,N,N'-caprolactam disulfide and the like.

The sulfur cure accelerators which may be employed include thioureas,such as N,N'-dibutylthiourea, 2-mercaptoimidazoline, tetramethylthioureaand the like; guanidine derivatives, such as N,N'-diphenylguanidine andthe like; xanthates, such as zinc dibutylxanthate and the like;dithiocarbamates, such as zinc dimethyldithiocarbamate, zincdiethyldithiocarbamate, zinc dibutyldithiocarbamate, sodiumdiethyldithiocarbamate, and the like; thiuramsulfides, such asdipentamethylenethiuram disulfide, dipentamethylenethiuram hexasulfide,tetrabutylthiuram monosulfide, tetramethylthiuram monosulfide,tetraethylthiuram monosulfide, tetraethylthiuram disulfide and the like;heterocyclics, such as mercaptobenzimidazole, mercaptobenzthiazole,2,2'-dibenzothiazyl disulfide, zinc 2-mercaptobenzothiazole and thelike; and sulfenamides, such asN-oxydiethylene-2-benzothiazolesulfenamide,N-t-butylbenzothiazylsulfenamide, N-cyclohexyl2-benzothiazylsulfenamide,N,N-diisopropyl-2-benzothiazylsulfenamide and the like. Moreover,mixtures of two or more sulfur cure accelerators may be employed in thecuring agent. The preferred accelerators are thiazoles and sulfenamides,with sulfenamides being particularly preferred.

The peroxides which may be employed in this invention have an activationtemperature which is below the decomposition temperature of the rubbersemployed. Illustrative of such peroxides are benzoyl peroxide, dibenzoylperoxide, 1,3-bis(t-butylperoxyisopropyl)benzene, diacetyl peroxide,butyl 4,4-bis(t-butylperoxy)valerate, p-chlorobenzoyl peroxide, cumenehydroperoxide, t-butyl cumyl peroxide, t-butyl perbenzoate, di-t-butylperoxide, dicumyl peroxide, 2,5-dimethyl-2,5-di-t-butylperoxyhexane,2,5-dimethyl-2,5-di-t-butyl-peroxyhex-3-yne,4-methyl-2,2-di-t-butylperoxypentane and the like. Mixtures of two ormore peroxides may also be employed. The preferred peroxides are dicumylperoxide and 2,5-dimethyl-2,5-di-t-butylperoxyhexane.

There are available on the market various packaged products known undertheir trademarks; mention may be made of:

Dicup 40, manufactured by Hercules Chemical Co., containing 40 percentdicumyl peroxide;

Perkadox Y12, manufactured by Noury van der Lande, containing 40 percentbis(tert.butylperoxy-isopropyl) benzene;

Peroximon F40, manufactured by Montecatini Edison, S.p.A., containing 40percent bis(tert.-butyl-peroxy) diisopropyl benzene;

Trigonox, manufactured by Noury van der Lande, containing 40 percent1,1-di-tert-butyl-peroxy 3,3,5-trimethyl cyclohexane;

Varox, manufactured by R. T. Vanderbilt Co., containing 50 percent2,5-dimethyl-2,4-bis(tert.-butyl peroxy) hexane; and

Luperko, manufactured by Wallace & Tiernan, Inc., containing 45 percent2,5-dimethyl-2,5-bis(tert.-butyl peroxy)hexyne-3.

Typically, between about 0.5 and about 200, preferably between about 5and about 150, and most preferably between about 6 and about 14, gramatoms of sulfur per mole of peroxide are present in said curing agent.

The sulfur cure accelerator is generally present in amounts of betweenabout 0.1 part and about 5 parts per 100 parts of rubber, withpreferably between about 0.3 part and about 3.0 parts of accelerator per100 parts of rubber being present. Most preferably, between about 0.3part and about 1.0 part of accelerator per 100 parts of rubber areemployed.

Generally, between about 0.2 and about 5, preferably between about 0.5and about 3, and more preferably between about 0.5 and about 1.5 partsof sulfur per hundred parts by weight of rubber are employed. Employingthe ratios of sulfur to peroxide stated above, one skilled in the artcan easily calculate the corresponding amount of the particular peroxidewhich is to be employed. Generally, however, the amount of organicperoxide to be used is from about 0.3 to about 10 parts by weight per100 parts by weight of elastomers, and preferably from about 0.3 toabout 5 parts by weight. These ranges are based on 100% active productand are adjusted for products with less active ingredient.

Preferably, the sulfur is employed in very small amount (From about 0.5to about 3.0 part by weight for every 100 parts by weight of elastomersis suitable with 1.0 to 3.0 part preferred for tires, which amount wouldnot be sufficient for vulcanization in the absence of peroxide andaccelerator.

The mixture includes, in addition to the elastomers and thevulcanization system, also the customary ingredients such asantioxidant, extender or plasticizing oil, fillers (carbon black,silica, titanium and zinc oxides), activators, retarders, in proportionssimilar to those found in sidewall rubbers, depending on the propertiesdesired. Thus, the mixtures contain from about 30 to about 65 parts byweight of carbon black per 100 parts by weight of total elastomer.

The vulcanization by the peroxides of sidewall blends having a base ofelastomers of the ethylene-propylene type associated with dieneelastomers along with the triazine compound of structure (I)surprisingly results in a number of advantages over thesulfur-vulcanization mixtures, namely:

1. Improvement in the resistance to ozone for an equal amount ofethylene-propylene elastomer. This advantage is the greater the moreethylene-propylenediene terpolymer is used and the higher its averagemolecular weight.

2. Improvement of the adherence to conventional rubber blends aftervulcanization. The sidewall rubber adheres better to the carcass and,therefore, without risk of internal separation in the sidewall, one canuse more elastomer of ethylene-propylene type and therefore enjoy betterprotection against ozone.

3. Improvement in the resistance to fatigue, particularly due toflexure.

The foregoing peroxide/sulfur cured blend of diene and EPDM is the mostpreferred form of polymer composition and curative. However, it is to benoted that the triazine of structure (I) is useful with conventionalsulfur vulcanizing systems as have been commonly used with dieneelastomer rubber carcassed tires. The general term "carcass" is usedhere as generally indicating all portions of the body of a bias orradial ply tire. Used as such, the carcass is composed of many, manydifferent layers of elastomer. Some of the elastomer layers includefabric, or cords or other types of reinforcements incorporated withinthe layer. Some of the many components of a tire carcass are mentionedby way of example only. The crown or tread area of the tire overlays acrown reinforcement area in which the primary belts are imbedded whichadds stability to the structure. Under the belts are the fabricreinforced innerplies which may be radially oriented or on a biasforming the body of the tire. Inward, from the carcass reinforcements,is the rubber inner liner layer. Now moving to the sidewall area, thesidewall may be formed of many layers but typically four layers areutilized moving from the crown down through the shoulder of the tire andeventually ending in the area of the bead. A radially inward first layernormally extends in varying thickness from the crown or tread area allthe way down to near the bead reinforcement area. Radially outward fromthat innermost layer are layers which may include a white sidewallportion with black outermost layers lying on either side of thewhitewall composition. It is these outermost sidewall layers in whichthe elastomer composition of this invention utilizing triazine ofstructure (I) is found to be most useful. The outermost sidewall layersare constantly exposed to the rigors of the environment and encountermillions of flex cycles during the life of a tire. It is highlydesirable for these outermost sidewall layers to maintain good physicalproperties as well as an aesthetically correct appearance. When a blacksidewall tire construction is being utilized, those outward layers areall black, the carbon black reinforced and it is highly desirable forthose layers to maintain a jet black, shiny surface throughout the lifeof the tire If a white sidewall composition is included in the outermostsidewall, this it is of course desirable that the white sidewall portionremain white and not turn yellow or brown upon aging. It is well knownthat when using normal quantities such as 2-8 parts per 100 of rubberhydrocarbon of conventional paraphenylenediamine antiozonants, the whitesidewall areas of a tire and even the black sidewalls undergo anaesthetically undesirable darkening with age and exposure to outdoorenvironmental conditions. The use of the triazine compounds of theinvention has been shown to minimize the development of this undesirablediscoloration in both white and black sidewall type elastomercompositions. The most preferred composition includes a base compositionof diene based unsaturated elastomers as well as an EPDM elastomer. Sucha combination withstands the ozone of the atmosphere for prolongedservice life of the tire carcass area. This is particularly important insuch applications as over-the-road truck tires where the tire carcassmay be retreaded four, five or six times during its life, and thecarcass may be required to go up to 1,000,000 miles of trouble freeservice.

The novel compounds of the invention may be used in combination withother antiozonants and less preferably with microcrystalline waxes asare commonly used to protect against static ozone attack. The otheranti-ozonants which may be utilized include any of the commonlyrecognized paraphenylenediamine class of materials:N-phenyl-N'-(1,3-dimethylbutyl)-p-phenylenediamine;N-phenyl-N'-isopropyl-p-phenylenediamine;N-phenyl-N'-(1-methylheptyl)-p-phenylenediamine;N-phenyl-N'-cyclohexyl-p-phenylenediamine; mixeddiarylp-phenylenediamines; N,N'-diphenyl-p-phenylenediamine:N,N'-di-beta-naphthyl-p-phenylenediamine;N,N'-bis(1,4-dimethylpentyl)-p-phenylenediamine;N,N'-bis(1-ethyl-3-methylpentyl)-p-phenylenediamine;N,N'-bis(1-methylheptyl)-p-phenylenediamine;N-phenyl-N'-p-toluenesulfonylp-phenylenediamine;N-phenyl-N'-alkyl-p-phenylenediamine;6-ethoxy-1,2-dihydro-2,2,4-trimethylquinoline; and nickel dibutyldithiocarbamate.

A most preferred antiozonant to be used in combination with the noveltriazine compounds of the invention isN-phenyl-N'-(1,3-dimethylbutyl)-p-phenylenediamine.

The novel compounds of the invention may be added to an unsaturatedpolymer at a level of from 0.1 to about 10 parts by weight per hundredparts by weight of rubber hydrocarbon (hereinafter PHR). For thesepurposes the polymer is assumed to be a natural or synthetic rubber. Amore preferred addition level is about 1 to about 8 parts PHR. The mostpreferred level is from about 2 to about 6 parts PHR. When the triazinecompounds of the invention are used in combination with otherantiozonants such as the paraphenylenediamine class of materials, theymay be added in a blend which totals to the ranges set forth above,although higher cumulative levels than the preferred ranges indicatedabove may be ideal when these blends are employed. The compounds of theinvention may be blended with the other antiozonants at ratios rangingfrom 1:3 to 3:1. More preferred is a ratio range of 2:3 to 3:2. Theseratios are meant to indicate the percentages are 40:60 to 60:40 where inall cases the triazine compounds of the invention are the first numberof each ratio. The most preferred is about 50:50. It should be notedthat in certain applications and with certain other antiozonants, thePHR ranges of antiozonant listed above may be varied in order to obtainthe optimal protection. Reasonable experimentation must be undertaken inorder to optimize the ratios and overall levels of the blend when thetriazine compounds of the invention are blended with other conventionalantioxidants and antiozonants.

The novel triazine compounds of the invention may be synthesized by asuitable synthesis route. The following synthesis examples are providedto illustrate a currently preferred method of manufacturing certain ofthe class of triazine compounds (I) of the invention.

SYNTHESIS OF TRIAZINE COMPOUNDS EXAMPLE 1:2,4,6-tris(N-1,4-dimethylpentyl-p-phenylene diamino)-1,3,5-triazine

In a 3-liter, four-necked, round-bottomed flask equipped with athermometer, a mechanical stirrer, a condenser, and a dropping funnelwas placed 1500 ml of isopropanol. The ispropanol was cooled to -10° C.and 184.4 grams (1 mole) of cyanuric chloride was added. To this stirredsuspension was added 680 grams (3.3 moles) of 4-amino-N-(1,4dimethylpentyl)aniline dropwise over 1 hour period keeping thetemperature between -10° and -5° C. Over 1 hour the reaction mixture waswarmed to 30° C. then held for 16 hours at 30° C. The reaction mixturewas refluxed for 1 hour at about 80° C. The reaction was followed byhigh pressure liquid chromatograph by observing the disappearance of thestarting amine, and the conversion of the intermediate mono- and bis-substituted compounds to the final tris-substituted product. Aftercooling to 60° C. 240 grams (3 moles) of 50 percent sodium hydroxidesolution was added dropwise over 1 hour period. The sodium chloride wasremoved by filtration at 40° C. The filtrate was cooled to 10° C. andthe solvent was decanted off. The oily lower layer was extracted withwater at 60° C. then crystallized from fresh isopropanol. The titlecompound was recrystallized from hexane and it melted at 128°-132° C.The yield was 78.1 percent. The infrared spectrum was consistent withthe structure. Relative area HPLC analysis of the product showed it tobe 95.8 percent pure.

EXAMPLE 2: 2,4,6-tris(N-isopropyl-p-phenylenediamino)1,3,5-triazine

In a 2-liter, four-necked, round-bottomed flask equipped with athermometer, a mechanical stirrer, a condenser, and a dropping funnelwas placed 650 ml. of isopropanol. The isopropanol was cooled to -5° C.and 36.8 grams (.2 mole) of cyanuric chloride was added. To this stirredsuspension was added a solution of 90 grams (0.6 mole) of4-amino-N-isopropylaniline in 100 ml. of isopropanol dropwise over 1hour period keeping the temperature between -5 and 0° C. Over 1/2 hourthe reaction mixture was warmed to 30° C. then refluxed for 2 hours. Thereaction was followed by high pressure liquid chromatography byobserving the disappearance of the starting amine, and the conversion ofthe intermediate mono- and bis-substituted compounds to the finaltris-substituted product. The reaction mixture was cooled, and allowedto stand overnight. The amine hydrochloride salt was neutralized byadding 96 grams (0.6 mole) of 25 percent sodium hydroxide solution over1/2 hour period, and then refluxing the mixture for 1/2 hour. The titlecompound precipitated upon cooling and was isolated by filtration,washed with isopropanol and hot water (60° C.), M.P. 196°-198° C. Theyield was 75.2 percent. The infrared spectrum was consistent with thestructure. Relative area HPLC analysis of the product showed it to be95.3 percent pure.

EXAMPLE 3: 2,4,6-tris(N-cyclohexyl-p-phenylenediamino)-1,3,5-triazine

The procedure of Example 2 was repeated except on a 0.1 molar scale with4-amino-N-cyclohexylaniline used to produce the title compound, M.P.215°-217° C. The yield was 89.9 percent. The infrared spectrum wasconsistent with the structure. Relative area HPLC analysis of theproduct showed it to be 90.1 percent pure.

EXAMPLE 4: 2,4,6-tris(N-sec-butyl-p-phenylenediamino)-1,3,5-triazine

The procedure of Example 2 was repeated except that4-amino-N-sec-butylaniline was used to produce the title compound, M.P.167°-169° C. The yield was 90.8 percent. The infrared spectrum wasconsistent with the structure. Relative area HPLC analysis of theproduct showed it to be 94.6 percent pure.

EXAMPLE 5: 2,4,6-tris(N-1,3-dimethylbutyl-p-phenylenediamino)-1,3,5-trazine

In a 3-liter, four-necked, round-bottomed flask equipped with athermometer, a mechanical stirrer, a condenser, and a powder funnel wasplaced a solution of 316.8 grams (1.65 moles) of 4-amino-N-(1,3dimethylbutyl)aniline in 1500 ml of isopropanol. The temperature of thesolution was adjusted to 30° C. and 92.2 grams (0.5 mole) of cyanuricchloride was added over 1/2 hour period keeping the temperature between30° to 40° C. The reaction mixture was refluxed for 1-1/2 hours. Thereaction was followed by high pressure liquid chromatography byobserving the disappearance of the starting amine, and the conversion ofthe intermediate mono- and bis-substituted compounds to the finaltris-substituted product. After cooling the reaction mixture to 60° C.120 grams (1.5 moles) of 50 percent sodium hydroxide solution was addeddropwise over 1 hour period. The sodium chloride was removed byfiltration at 40° C. The filtrate was charged back to the reactionflask, and 250 ml of water was added dropwise. The title compoundprecipitated, and was removed by filtration, M.P. 124°-127° C. The yieldwas 82.6 percent. The infrared spectrum was consistent with thestructure. Relative area HPLC analysis of the product showed it to be95.3 percent pure.

EXAMPLE 6:2,4,6-tris(N-1-methylheptyl-p-phenylenediamino)-1,3,5-triazine

The procedure of Example 5 was repeated except on a 0.225 molar scalewith 4-amino-N-(1-methylheptyl)aniline used to produce the titlecompound. After recrystallization from a 28 percent toluene hexanemixture the melting point of the product was 87°-90° C. The infraredspectrum was consistent with the structure, and the relative area HPLCanalysis of the product showed it to be 90.7 percent pure.

EXAMPLE 7:2,4,6-tris(N-2,4-di-tert-butylcyclohexyl-p-phenylenediamino)-1,3,5-triazine

The procedure of Example 5 was repeated except on a 0.25 molar scalewith 4-amino-N-(2,4-di-t-butylcyclohexyl)aniline used to produce thetitle compound, M.P. 147°-152° C. The yield was 85.7 percent. Theinfrared spectrum was consistent with the structure.

EXAMPLE 8:2,4,6-tris(N-2-sec-butylcyclohexyl-p-phenylenediamino)-1,3,5-triazine

The procedure of Example 5 was repeated except on a 0.25 molar scalewith 4-amino-N-(2-sec-butylcyclohexyl)-aniline used to produce the titlecompound. The product didn't crystallize, and was isolated as a potresidue, M.P. 122°-130° C. The yield was 95.8 percent. The infraredspectrum was consistent with the structure, and the relative area HPLCanalysis of the product showed it to be 86.6 percent pure.

ANTIOZONANT UTILITY EXAMPLES 9-24

The N-alkylarylenediamino triazine compounds of the invention functionas outstanding antiozonants in rubber polymers with no migratorystaining tendency evident at this time. The following examplesdemonstrate their utility in a variety of ozone and color stability testregimes. All tests utilize the triazines in vulcanized rubber compoundsas are typical in the industry. The following test formulation is atypical rubber compound.

    ______________________________________                                        TEST FORMULATION                                                                               Parts by Weight                                              ______________________________________                                        Natural Rubber (SMR5CV)                                                                          50.0                                                       Polybutadiene (cis 1,4 BR)                                                                       50.0                                                       Carbon Black (N-326)                                                                             50.0                                                       Zinc Oxide         3.0                                                        Microcrystalline Wax                                                                             1.5                                                        Stearic Acid       1.0                                                        Aromatic Oil       5.0                                                        Benzothiazole Sulfenamide                                                                        1.0                                                        Sulfur             2.0                                                        Antiozonant - Variable                                                                           Variable                                                   ______________________________________                                    

    ______________________________________                                        TABLE OF ANTIOZONANTS                                                         ______________________________________                                        Comparative A                                                                           N-phenyl-N'-(1,3-dimethylbutyl)-p-                                            phenylenediamine (commercially available as                                   Flexzone ™ 7F from Uniroyal Chemical                                       Company)                                                            Comparative B                                                                           mixed diaryl -p-phenylenediamine                                              (commercially available as Novazone ™ AS                                   from Uniroyal Chemical Company)                                     Example 1 2,4,6-tris(N-1,4-dimethylpentyl-p-phenylene-                                  diamino)-1,3,5-triazine                                             ______________________________________                                    

The foregoing test formulation was used for all test samples unlessotherwise noted. The formulation is an approximation of a typical tiresidewall compound. The identity and level of the antiozonant are thevariables to be evaluated in the subsequent examples.

The test formulation was utilized to make uncured test sheets bypreblending the natural rubber and polybutadiene. Once blending wasaccomplished, all other ingredients except the sulfur and benzothiazolesulfenamide were added to form a nonproductive compound and in asubsequent mixing step, the foregoing ingredients were added. Testssheets for the subsequent testing were cured in a platen press betweenheated plates for a time sufficient to achieve full cure. For thepurposes of testing, a fifteen minute cure at 160° C. was normallyutilized. The exact sample configuration of the test specimens for theozone testing varies by the description of the ASTM method utilized.Reference is made to the ASTM test methods and such methods areincorporated herein by reference to abbreviate the required descriptiveinformation regarding specimen preparation, test methods and testresults.

OZONE TEST RESULTS

Ozone testing was conducted utilizing the standard test method of ASTMD1149-81 which is titled Rubber Deterioration - Surface Zone Cracking ina Chamber (Flat Specimen). This method covers the estimation of theresistance of vulcanized rubber to cracking when exposed to anatmosphere containing ozone. Rubber specimens are kept under a surfacetensile strain and the ozone content in the test chamber is maintainedat a 50 part per hundred million level in a 100° F. (38° C.) testchamber. A common designation for this test is the bent loop test methodsince the test specimen is placed under strain by having it clamped in alooped configuration in which varying degrees of strain and elongationresult. This bent loop configuration is an extremely severe testconfiguration in which failure can be expected in a relatively few hoursgiven the high temperature and high ozone atmosphere in which the testsamples are placed.

                  TABLE I                                                         ______________________________________                                        STATIC OZONE TESTING                                                          (Results in Hours)                                                                            EXAMPLE #                                                                     9     10         11                                                           ANTIOZONANT, 4 PHR                                                                      Comparative                                                                              Exam-                                    OZONE BOX - STATIC TEST                                                                         Blank   A          ple 1                                    ______________________________________                                        Unaged                                                                        No Cracks         --      --         1128                                     Cracked           6       600        --                                       6 Months Aged                                                                 No Cracks         --      --         1080                                     Cracked           8       24         --                                       12 Month Aged                                                                 No Cracks         --      --         1040                                     Cracked           17      40         --                                       ______________________________________                                    

The prepared specimens were aged unstressed at room temperature at sixmonths and twelve months and tested. Accordingly, three sets of testdata are presented: unaged, six month and twelve month aged. The Example9 column headed by the term blank denotes a formulation which containsno antiozonant protection. That unprotected sample broke in between sixand seventeen hours of exposure depending upon the degree of aging whichthe specimen underwent prior to ozone exposure. Example 10 withComparative A is the result of the conventional paraphenylenediamine(Flexzone 7F) added at four parts PHR and it cracked between 600 and aslow as 24 hours of exposure. In Example 11, the rubber formulationprotected by the substituted triazine of the invention shown in Example1 survived between 1040 and 1128 hours for the various unaged and agedsamples. It is clear from these results that the ozone protectionafforded by the compounds of this invention are outstanding compared tothe conventional antiozonants which are well known in the rubber field.

Table II shows the data for static ozone testing conducted in a similarmanner to the testing shown in Table I. Test specimens dumbells, 3mm by50 mm were stretched 20% on specially designed racks and the degree ofcracking was periodically recorded. Under this method, the test sampleis subjected to the ozone atmosphere of 50 parts per hundred million at100° F. while under 20% elongation or extension. This additional degreeof strain is a added characteristic of the sample preparation that isdifferent than the test conducted as shown in Table I. All other detailswith respect to the test method are similar to those previously reportedfor the Table I results.

                  TABLE II                                                        ______________________________________                                        OZONE EXPOSURE 20% EXTENSION                                                  (Results in Hours)                                                                    EXAMPLE #                                                                       12        13            14                                                  ANTIOZONANT, 4 PHR                                                                    COMPARATIVE   EXAMPLE                                                 BLANK   A             1                                               ______________________________________                                        Unaged                                                                        No Cracks --        600*          1128                                        Cracked   552       --                                                        6 Months Aged                                                                 No Cracks --        --            1080                                        Cracked    8        24                                                        12 Month Aged                                                                 No Cracks --        --            1040                                        Cracked    12       56            --                                          ______________________________________                                         *Very slight cracking is visible                                         

The unprotected blank test specimens of Example 12 survived between 8and 552 hours depending on how long the sample was aged. The ComparativeA composition when in an unaged condition at 600 hours showed veryslight cracking. The six month and twelve month aged Example 13 showedcracking of the sample in between 56 and 24 hours. The compounds of thisinvention shown as example #14 again showed very dramatic improvementsover the prior art antiozonant in providing protection which exceeded1000 hours at these test conditions. This again demonstrates thesuperiority of the N-alkyl arylenediamino triazines of this inventionover the conventionally used antiozonant of the paraphenylenediamineclass.

Rubber articles must be protected against ozone when they are subjectedto such exposure on outdoor weathering. One of the most difficultapplications is on a tire where the vehicle remains outdoors and inozone bearing atmosphere for an indefinite period of time. The trueservice conditions under which tires operate are not well duplicated byeither static ozone tests such as those described in Table I and II norare they well duplicated using dynamic test procedures such as DeMattiaFlex Testing. In an effort to simulate a typical tire surface conditionthe following test method is utilized. In the testing scheme, samplesare mounted in southern facing test fixtures outdoors, exposed to thefull outdoor environmental conditions as are present in Naugatuck, Conn.The samples are continuously flexed for 8 hours over approximately a 78°angle. After this flexing period the sample is then relaxed and remainsin that relaxed, static condition for 16 hours. This protocol isrepeated day after day until the deterioration as evidenced by theappearance and growth of cracks on the sample surface is observed andrecorded. This intermittent flex/relaxation test is felt to correlatewell with the actual conditions under which a tire operates. That is,the tire is driven for a number of hours in which it is cycled tosimilar extensions as are accomplished during the flexing portion of thetest. Then the tire sits for a prolonged period of time in a staticcondition which is reproduced in the 16 hour static portion of thecycle. The test results are expressed in kilocycles. During the flexingportion of the test, the samples are flexed through a 78° angle at about8.5 kilocycles per hour.

                  TABLE III                                                       ______________________________________                                        DYNAMIC OZONE TESTING                                                         (Results in Kilocycles)                                                                       EXAMPLE #                                                                     15    16         17                                           8 HOUR FLEX/      ANTIOZONANT, 4 PHR                                          16 HOUR STATIC            Comparative                                                                              Exam-                                    RESULTS IN KILOCYCLES                                                                           Blank   A          ple 1                                    ______________________________________                                        Unaged                                                                        No Cracks         --      --                                                  Cracked           1694    8264       8584                                     .sup.1 6 Months Aged                                                          No Cracks         --      13896*     16588*                                   Cracked           2969    --         --                                       .sup.1 12 Month Aged                                                          No Cracks         --       7655*      7655*                                   Cracked           1165                                                        ______________________________________                                         .sup.1 Test ongoing                                                           *Very, very slight cracking is visible                                        Note:                                                                         No microcrystalline wax in 15, 16, 17.                                   

This dynamic flexing test uses rectangular specimens 12 mm by 76 mm witha 3 mm radius circular groove across the center of the specimen.

It is apparent from the results, that Example 15 which contained noantiozonant survived less than 3000 kilocycles under this test. Examples16 and 17, which are protected by the paraphenylenediamine of the priorart and a triazine of this invention, respectively, exhibited verysignificant improvements in the ability to withstand the outdoor aging.The triazine compound of the invention protected the sample of Example17 with very nearly the same result as the paraphenylenediamine ofComparative A, which is generally considered to be one of the bestantiozonants available for dynamic applicants.

ANTIOZONANT BLENDING--EXAMPLES 18-21

The triazine compounds of the invention, when compared toN-phenyl-N'-(1,3-dimethylbutyl)-p-phenylenediamine (Comparative A -Flexzone 7F) generally exhibit much better protection under staticconditions and slightly poorer protection under severe dynamicconditions as judged by various laboratory test methods. However, it hasbeen quite unexpectedly and surprisingly found that the dynamicprotection properties may be greatly improved by blending the triazinecompounds with conventional p-phenylene diamines. This is accomplishedwithout sacrificing static condition ozone protection. Examples 18-21below demonstrate this synergistic effect.

In Examples 18 and 19, the antiozonant of Example 1 was blended with twoconventional antiozonants to evaluate the cumulative effect under bothstatic and dynamic ozone testing conditions. The results were comparedto unblended controls 20 and 21. The rubber formulation utilized was thesame as the Test Formulation previously used in all test work exceptthat the microcrystalline wax was deleted to assure that the antiozonanteffect of the wax was not present to affect the results.

The Outdoor Dynamic Ozone test was conducted in a similar manner to the8 hour flex/16 hour static test for Examples 12-14 of Table III exceptthat the flexing at 8.5 kilocycles per hour is run continuously. Thereis no relaxation period. The rest was ongoing, and therefore, no sampleshave yet reached the point of final cracking (failure).

The Ozone Box Static Test was run as described for Examples 9-11.

                  TABLE IV                                                        ______________________________________                                        ANTIOZONANT BLEND TESTING                                                                  EXAMPLE #                                                                     18     19       20       21                                      ______________________________________                                        ANTIOZONANT, PHR                                                              Example 1      2.5      3.0      --     4.0                                   Comparative A  --       1.0      4.0    --                                    Comparative B  1.5      --       --     --                                    OZONE BOX STATIC                                                              TEST (in hours)                                                               No Cracks      1016     1016     --     1016                                  *VVS           --       --       --     --                                    Cracked        --       --       216    --                                    OUTDOOR DYNAMIC                                                               TEST Continuous Flexing                                                       (in kilocycles)                                                               No Cracks       14583**  14583** 14583**                                                                              --                                    *VVS           --       --       --     4231                                  Cracked        --       --       --     --                                    ______________________________________                                         *VVS -- First appearance of very, very slight cracks                          **Test still underway last reading at 14583 kilocycles.                  

The results shown in Table IV for the Ozone Box Static Test show thatComparative A (Flexzone 7F) cracks after 216 hours (Example 20) whilethe compound of Example 1, used in Examples 18, 19, 21 alone or incombination with Comparative A or B afforded excellent protection asindicated by the fact that no cracks were evident after 1016 hours.

The Outdoor Dynamic Test results of Examples 18-20 show that the blendsof Example 1 with Comparative A and B showed excellent protection underdynamic conditions. The blends of Examples 18 and 19 unexpectedlyimproved the Dynamic Ozone resistance compared to Example 21 which usedthe compound of Example 1 alone.

NON-STAINING CHARACTERISTICS - EXAMPLES 22-24

Samples specimens were prepared using the test formulation set forthpreviously but without wax. The test formulation was compounded, mixedand cured into flat test sheets for subsequent analysis of discolorationand staining characteristics. The specific testing was conducted inaccordance ASTM-D925-83 Method C. The Method C judges the degree ofstaining tendency of material by determining the amount of discolorationthat occurs from the substrate material through a white lacquer coatingwhich has been placed on the test sample. The test formulationpreviously set forth for all test samples of the invention was utilized.Once the test specimen was mixed and cured, it was coated with a veneerof white lacquer in accordance with the ASTM-D925 procedure. It was thenexposed to a sunlamp light source in a suitable test chamber for aspecified period of time. The Hunter Lab™ Colorimeter test apparatus wasutilized to objectively determine the change in the color of the whitelacquer during the four-hour exposure to the sun lamp. ASTM D2244-79titled "Color Differences of Opaque Materials", reports a number ofcharacteristics by the standard difference letters a, b, and L. Sincethe staining characteristics of normal antiozonants are very extreme,the L color scale is reported below. The L color scale is a scale from 0to 100 with a 0 value being totally black and a 100 value being purewhite. Therefore the higher the L value, the whiter the sample. The Testformulation of Example 22 was prepared as a blank which contain noantiozonant. Example 24 contains the antiozonant of the inventiondescribed in Example 1,2,4,6-tris(N-1,4-dimethylpentyl-p-phenylenediamino)-1,3,-5-triazine.

Example 23 uses the Comparative A material which isN-phenyl-N'-(1,3-dimethylbutyl)-p-phenylenediamine (Flexzone 7F,available from Uniroyal Chemical Company, Inc.). The test results of thethree samples are presented below in Table V showing the Hunter "L"value after four hours of exposure.

                  TABLE V                                                         ______________________________________                                        HUNTER "L" COLOR RESULTS                                                      EXAMPLE                                                                       22           23          24                                                   ANTIOZONANT                                                                   blank        Comparative A                                                                             Example 1                                            ______________________________________                                        87.9         32.6        81.5                                                 ______________________________________                                    

The results shown above clearly show that the conventionalparaphenylenediamine material of Example 23 shows significant staining(32.6) after 4 hours of exposure. But by contrast the test formulacontaining the compound of the invention of Example 1 had a color valueof 81.5 which is very close to 87.9 value reported for the blank ofExample 22. Thus, the compound of the invention is shown to have minimaldiffusion staining which is an extremely unusual result for stabilizerof the amine class. Thus, the compounds of the invention can beadvantageously utilized as antiozonants without the normal accompanyingproblems of diffusion staining and severe discoloration such as thatshown in Comparative A results above. This class of materials could bedescribed as non-staining antiozonants.

The compounds of the invention may be used to good advantage withantioxidants and antiozonants of the prior art in blends to enhanceparticular properties. While the substituted triazine compounds of theinvention have herein described only as antiozonants, it is clear thatthe materials may also function as antioxidants for rubber, thusproviding protection against oxidative degradation as well as ozoneprotection. It is noted that when used as an antioxidant, the levels aretypically much lower per hundred parts of rubber hydrocarbon than whenantiozonant protection is required.

Unsaturated polymers may be optionally protected against both oxidativeand ozone degradation by blending the triazine compounds of theinvention with conventional antioxidants. Many classes of phenolics,amines, etc. function as antioxidants. The Index of CommercialAntioxidants and Antiozonants, 3rd Edition published by The GoodyearTire and Rubber Company lists materials commonly viewed as materialshaving antioxidant properties, and is incorporated herein by reference.Representative classes of such antioxidant materials are stericallyhindered phenols, alkyl-substituted diphenylamines, aryl-substituteddiphenylamines, aralkylsubstituted diphenylamines, naphthylamines,reaction products of a diarylamine and a ketone, mono-phenols,bisphenols, polyphenols, hydroquinone derivatives, and polymerizedquinolines. The antioxidant system may contain one or more of thesematerials. Optimal levels of addition (PHR) for the antioxidants can beeasily determined through routine experimentation and may vary widelydepending upon the end use application.

The 2,4,6-tris(N-alkyl-p-phenylenediamino)-1,3,5-triazines can be mostadvantageously used in a tire as a component of any or all of thethermosetting rubber-containing portions of the tire. These include thetread, sidewall and carcass portions of a truck, passenger or off-roadvehicle tire which also contain many different reinforcing layerstherein. These components typically contain more than one thermosettingrubber polymer in a blend which must be protected from ozone degration,as well as oxidative attack.

Methods of incorporating these compounds into the tire are conventionaland well known. These compounds improve the scorch safety of the rubberstock in which they are incorporated compared to conventionalparaphenylenediamines.

TIRE SIDEWALL COMPOSITIONS--EXAMPLES 25-33

The following examples illustrate the preferred utility of the triazinesin pneumatic tire exterior sidewall compounds containing blends ofhighly unsaturated rubber as well as EPDM which has lesser unsaturation.

Examples 25, 26 and 27 are comparative examples, not within the scope ofthe invention. Example 25 does not contain either the essential triazinecomponent (I) of the invention or EPDM. Examples 26 and 27 have notriazine. These controls show cracking in the 72 hour ozone belt test(ASTM D-3395B-82) which is an extremely severe dynamic ozone test methodin which the compound samples are vulcanized onto a fabric belt.

                                      TABLE VI                                    __________________________________________________________________________                      EXAMPLE #                                                                     25 26 27  28  29   30   31   32   33                        __________________________________________________________________________    Natural Rubber (SMR 5CV)                                                                        60.00                                                                            60.00                                                                            60.00                                                                             60.00                                                                             60.00                                                                              60.00                                                                              60.00                                                                              60.00                                                                              60.00                     Polybutadiene (Cis 1,4-BR)                                                                      40.00                                                                            30.00                                                                            10.00                                                                             10.00                                                                             30.00                                                                              25.00                                                                              25.00                                                                              25.00                                                                              20.00                     EPDM.sup.1        -- 10.00                                                                            30.00                                                                             30.00                                                                             10.00                                                                              15.00                                                                              15.00                                                                              15.00                                                                              20.00                     Carbon Black (N-326)                                                                            45.00                                                                            45.00                                                                            45.00                                                                             45.00                                                                             45.00                                                                              45.00                                                                              45.00                                                                              45.00                                                                              45.00                     Naphthenic oil (Circosol 4240)                                                                  12.00                                                                            12.00                                                                            22.50                                                                             22.50                                                                             12.00                                                                              12.00                                                                              12.00                                                                              12.00                                                                              12.00                     Zinc Oxide        5.00                                                                             5.00                                                                             5.00                                                                              5.00                                                                              5.00 5.00 5.00 5.00 5.00                      Stearic Acid      1.50                                                                             1.50                                                                             1.50                                                                              1.50                                                                              1.50 1.50 1.50 1.50 1.50                      Triazine Antiozonant.sup.2                                                                      -- -- --  2.00                                                                              2.00 2.00 3.50 2.50 2.00                      Antiozonant.sup.3 -- -- --  --  1.50 1.50 1.50 1.50 1.50                      2(Morpholinothio)benzothiazole                                                                  0.70                                                                             0.70                                                                             0.70                                                                              0.70                                                                              0.70 0.70 0.70 0.70 0.70                      Sulfur (80% oiled)                                                                              2.25                                                                             2.25                                                                             2.25                                                                              2.25                                                                              2.25 2.25 2.25 2.25 2.25                      Mooney Scorch @ 132° C. (270° F.)                               ASTM D-1646                                                                   Scorch Time (minutes)                                                                           24.00                                                                            24.00                                                                            22.50                                                                             16.25                                                                             20.80                                                                              20.71                                                                              20.56                                                                              20.29                                                                              19.19                     Cure Rate (minutes)                                                                             14.25                                                                            24.25                                                                            10.00                                                                             6.45                                                                              13.90                                                                              12.76                                                                              10.67                                                                              10.75                                                                              10.76                     Monsanto Fatigue Flex                                                                           73.90                                                                            67.60                                                                            134.10                                                                            117.80                                                                            84.30                                                                              99.40                                                                              84.00                                                                              75.10                                                                              89.00                     ASTM D-4482-85 KC to Failure                                                  Cured 18 Minutes @ 150° F.                                             (aged 70 hours @ 100° C.)                                              DeMattia Flex Cracking                                                                          NR.sup.4                                                                         NR NR  NR  1236 1084 898  730  1354                      ASTM D-430-73 Method B                                                        Ozone Exposure                                                                ASTM D-1149-81                                                                Bent Loop @ 50 pphm/38° C.                                             (hours)                                                                       OK                NR NR NR  NR            1080 1080 1080                      VVS                             4    8                                        VS                              8    --                                       S                               --   96                                       C                               96   456                                      Dynamic Ozone Belt at 50 pphm                                                                   C  C  VVS OK  NR   NR   NR   NR   NR                        ASTM D-3395B-82                                                               @ 38° C., 72 continuous hours                                          Crack Rating                                                                  __________________________________________________________________________     .sup.1 Ethylenepropylene-5-ethylidene-2-norbornene terpolymer: E/P wt.        ratio = 66/34; diene wt. % = 82; IV = 26 dl/g (decalin @ 135° C.);     Mooney Viscosity (ML 1 + 4 @ 100° C.) = 65 on 75 phr oil extended      polymer. All oil reported in naphthenic oil line below.                       .sup.2 2,4,6tris(N-1,4-dimethylpentyl-p-phenylenediamino)-1,3,5-triazine      (See Example 1 for synthesis).                                                .sup.3 Mixed diarylp-phenylenediamine (commercially available as Novazone     ™ AS from Uniroyal Chemical Company, Inc.                                  .sup.4 NR -- not run.                                                         .sup.5 OK -- no cracks; VS -- very slight cracks; VVS -- very, very sligh     cracks; S -- slight cracks and C -- cracked.                             

The belt is run over a set of pulleys to induce a surface strain in anozone chamber at 50 parts per hundred million of ozone at 100° F.

Examples 25 and 26 cracked during the ozone belt exposure while Example27 showed an improved result (very, very slight cracking) due to thepresence of the EPDM.

Example 28 dramatically illustrates the advancement in the art of rubbercompounding. This compound, having both the essential triazine and theEPDM survived the

severe dynamic ozone test with no cracking whatsoever.

Examples 29-33 illustrate the importance of the levels of addition ofthe essential EPDM and triazine components of the invention. Withoutbeing held to the scientific validity of the explanation, it iscurrently felt that optional protection can be obtained by havingadequately high levels of either EPDM or the triazine compound. It isnot felt to be necessary to have high levels of both to obtainexceptional dynamic ozone and fatigue properties. However, it is to benoted that good to excellent ozone resistance can be obtained in thelower ranges of either critical component compared to other non-stainingozone protection methods.

The effect of progressively higher levels of the triazine compound (ofExample 1) is shown by looking at the ozone exposure (bent loop test)results of Examples 29 and 30 (two parts of triazine compound) whichshow cracks developing during the test. While the higher addition levelsof Examples 31 and 32 show no cracking through the 1080 hours of thetest.

The positive effect of progressively higher levels of EPDM is shown bycomparing Examples 29, 30 and 33 which have progressively more EPDM. Thelevel of ozone protection goes up with the EPDM level. The essentialtriazine compound is present at a constant level in these threeexamples. Thus, it can be concluded that desirable properties can beobtained by varying the level of lesser unsaturation elastomer (i.e.EPDM) and triazine compound.

                                      TABLE VII                                   __________________________________________________________________________                     EXAMPLE #                                                                     34  35  36 37  37 39  40  41                                 __________________________________________________________________________    Natural Rubber (SMR 5CV)                                                                       50.00                                                                             50.00                                                                             50.00                                                                            50.00                                                                             50.00                                                                            50.00                                                                             60.00                                                                             60.00                              Polybutadiene (PBD 1203)                                                                       50.00                                                                             20.00                                                                             50.00                                                                            20.00                                                                             20.00                                                                            20.00                                                                             --  --                                 EPDM.sup.1       --  30.00                                                                             -- 30.00                                                                             30.00                                                                            30.00                                                                             40.00                                                                             40.00                              Carbon Black (N-326)                                                                           50.00                                                                             50.00                                                                             50.00                                                                            50.00                                                                             50.00                                                                            50.00                                                                             50.00                                                                             50.00                              Naphthenic oil (Circosol 4240)                                                                 10.00                                                                             30.00                                                                             10.00                                                                            30.00                                                                             30.00                                                                            30.00                                                                             36.00                                                                             36.00                              Zinc Oxide        5.00                                                                              5.00                                                                              5.00                                                                             5.00                                                                              5.00                                                                             5.00                                                                              5.00                                                                              5.00                              Stearic Acid      1.50                                                                              1.50                                                                              1.50                                                                             1.50                                                                              1.50                                                                             1.50                                                                              1.50                                                                              1.50                              Triazine Antiozonant.sup.2                                                                     --  --   4.00                                                                             4.00                                                                              2.00                                                                             2.00                                                                             --   4.00                              N-t-butyl-2-benzothiazole                                                                       1.00                                                                              1.00                                                                              1.00                                                                             1.00                                                                              1.00                                                                             0.85                                                                              0.85                                                                              0.85                              sulfenamide                                                                   Dicumyl Peroxide (60%)                                                                         --  --  -- --  --  1.00                                                                              1.00                                                                              1.00                              Sulfur (80%)      2.00                                                                              2.00                                                                              2.00                                                                             2.00                                                                              2.00                                                                             1.50                                                                              1.50                                                                              1.50                              Mooney Scorch @ 132° C. (270 F.)                                       ASTM 1646                                                                     Scorch Time (minutes)                                                                          24.00                                                                             28.75                                                                             27.50                                                                            28.00                                                                             30.00                                                                            22.50                                                                             14.25                                                                             20.75                              Cure Rate (minutes)                                                                            12.50                                                                             10.50                                                                              7.50                                                                             5.50                                                                              5.75                                                                            15.25                                                                             12.75                                                                              9.00                              Monsanto Fatigue Flex                                                         ASTM-D-4482-85 KC to Failure                                                  Cured 18 Minutes @ 150° F.                                                               4.50                                                                             13.30                                                                             34.60                                                                            106.00                                                                            63.60                                                                            75.00                                                                             104.9                                                                             162.6                              (aged 70 hours @ 100° C.)                                              Static Adhesion @100° C.                                                                *   24.6                                                                              *  25.4                                                                              26.4                                                                             22.7                                                                              19.9                                                                              14.5                               Adhesion, kN/m   *19.6                                                                             21.6                                                                              *  23.6                                                                              26.9                                                                             *20.5                                                                             15.3                                                                              15.7                               __________________________________________________________________________     .sup.1 See Footnote 1, Table VI.                                              .sup.2 See Footnote 2, Table VI.                                              *Test sample slipped out of one of the grips.                            

EXAMPLES 34-41

Examples 34, 35, 36, and 40 are comparative examples not within thescope of this invention. 34, 35 and 40 have no triazine antiozonant and34 and 36 have no EPDM (lesser unsaturation polymer). The MonsantoFatigue Flex Results are very critical results which have a goodcorrelation to tire carcass life properties. Example 37 shows a flexfatigue value of 106 versus the much lower values of comparatives 34,35, 36 which are all missing at least one key component of theinvention.

The advantages of utilizing the preferred peroxide/sulfur combinationcuring system is shown by comparing the flex fatigue results ofcomparative example 35 (13.3) versus 39 and 41 (75 and 162.6). The curesystem selection is another important factor. Peroxide/sulfurcombination curing improves the flex fatigue results.

The importance of the triazine antiozonant is shown by comparing theflex fatigue value of comparative Example 35 (13.3) versus Example 37(106). Example 41 shows optimum flex fatigue results with high molecularweight EPDM, triazine antiozonant and peroxide/sulfur cure system.

In a tire a new compound is only useful if it has good adhesion toadjacent rubber layers of the tires. The static adhesion test resultsare consistently good for all stocks of the invention a value of 10 isgenerally considered fully adequate adhesion results. The adhesion ofcharacteristics of each compound of the examples were evaluated fortheir adhesion to the standard tread test formulation shown below inTable VIII. The test compound was plied up against the standard treadformulation with a ply of RFL treated fabric on both sides to form atest pad. The pad was press cured 15 minutes @177° C. The cured pad waspulled in a Scott tester (or Instron) to yield the force necessary tocause the test compound to separate from the standard test treadformulation. Duplicate samples were tested and reported in Table VII inkilonewtons/meter.

                  TABLE VIII                                                      ______________________________________                                        STANDARD TREAD TEST FORMULATION                                               FOR STATIC ADHESION TEST                                                      ______________________________________                                        Styrene Butadiene Rubber (SVR-1500)                                                                   55.0                                                  Polybutadiene (PBD 1203)                                                                              25.0                                                  Natural Rubber (SMR 5CV)                                                                              20.0                                                  Carbon Black (N-234)    55.0                                                  Zinc Oxide              3.0                                                   Microcrystalline Wax    0.5                                                   N-phenyl-N'(1,3-dimethylbutyl)-p-                                                                     1.0                                                   phenylenediamine                                                              Stearic Acid            1.0                                                   Aromatic Oil            20.0                                                  2-(Morpholinothio)benzothiazole                                                                       0.5                                                   Thiocarbamyl Sulfenamide                                                                              0.5                                                   Sulfur                  2.0                                                   ______________________________________                                    

In view of the many changes and modifications that may be made withoutdeparting from principles underlying the invention, reference should bemade to the appended claims for an understanding of the scope of theprotection afforded the invention.

What is claimed is:
 1. A thermosetting composition comprising anadmixture of:(a) at least one highly unsaturated rubbery polymer; (b) atleast one elastomer having lesser unsaturation than said highlyunsaturated rubbery polymer; (c) a compound of structure (I): ##STR4##in which R¹, R² and R³ are radicals independently selected from a C₃-C₁₈ branched or linear alkyl, or a C₃ -C₁₂ cycloalkyl or a C₃ -C₁₂cycloalkyl substituted with one or more C₁ -C₁₂ alkyl groups; (d) atleast one sulfur-containing cure component selected from the groupconsisting of elemental sulfur and a sulfur donor accelerator compound;and (e) at least one organic peroxide curative.
 2. A compositionaccording to claim 1 wherein said sulfur donor accelerator is selectedfrom the group consisting of 2-(4-morpholinyldithio)benzothiazole,tetramethylthiuram disulfide, tetraethylthiuram disulfide,dipentamethylene thiuram hexasulfide, and N,N'-caprolactam disulfide. 3.A composition according to claim 1 further comprising a sulfur cureaccelerator selected from the group consisting of thioureas, guanidinederivatives, zanthantes, dithiocarbamates, thiuramsulfides, thiazolesand sulfenamides.
 4. A composition according to claim 2 wherein saidsulfur donor accelerator is a thiazole or a sulfenamide.
 5. Acomposition according to claim 1 wherein said peroxide is selected fromthe group consisting of benzoyl peroxide, dibenzoyl peroxide,1,3-bis(t-butylperoxyisopropyl)benzene, dicetyl peroxide, butyl4,4-bis(t-butylperoxy)valerate, p-chlorobenzoyl peroxide, cumenehydroperoxide, t-butyl cumyl peroxide, t-butyl perbenzoate, di-t-butylperoxide, dicumyl peroxide, 2,5-dimethyl-2,5-di-t-butylperoxyhexane,2,5-dimethyl-2,5-di-t-butyl-peroxyhex-3-yne, and4-methyl-2,2-di-t-butylperoxypentane.
 6. A tire having a tread portionand a sidewall portion, said tire comprising:a rubber carcass includinga plurality of layers of thermosetting rubber polymers therein and aplurality of layers of reinforcing materials positioned within saidcarcass, at least one of said plurality of thermosetting rubber polymersbeing composed of at least one high unsaturated polymer blended with apolymer having lesser unsaturation to form a blend, said blend havingdispersed therein an antidegradant composition of: ##STR5## in which R¹,R² and R³ are radicals independently selected from a C₃ -C₁₈ branched orlinear alkyl, or a C₃ -C₁₂ cycloalkyl or a C₃ -C₁₂ cycloalkylsubstituted with one or more C₁ -C₁₂ alkyl groups.
 7. A tire accordingto claim 6 wherein said antidegradant composition further comprises aneffective amount of aN-phenyl-N'-(1,3-dimethylbutyl)-p-phenylenediamine;N-phenyl-N'-isopropyl-p-phenylenediamine;N-phenyl-N'-(1,4-dimethylpentyl)-p-phenylenediamine;N-phenyl-N'-(1-methylheptyl)-p-phenylenediamine;N-phenyl-N'-cyclohexyl-p-phenylenediamine; mixeddiarylp-phenylenediamines; N,N'-diphenyl-p-phenylenediamine;N,N'-di-beta-naphthyl-p-phenylenediamine;N,N'-bis(1,4-dimethylpentyl)-p-phenylenediamine;N,N'-bis(1-ethyl-3-methylpentyl)-p-phenylenediamine;N,N'-bis(1-methylheptyl)-p-phenylenediamine;N-phenyl-N'-p-toluenesulfonyl-p-phenylenediamine.
 8. A tire according toclaim 7 wherein said antidegradant composition further comprises:anantioxidant system incorporated into said polymer, said antioxidantsystem having one or more materials selected from the group of materialsexhibiting antioxidant properties consisting of sterically hinderedphenols, alkyl-substituted diphenylamines, aryl-substituteddiphenylamines, aralkyl-substituted diphenylamines, naphthylamines,reaction products of a diarylamine and a ketone, mono-phenols,bisphenols, polyphenols, hydroquinone derivatives, and polymerizedquinolines.
 9. A tire according to claim 6, wherein said sidewallportion of said rubber carcass includes in said plurality ofthermosetting rubber polymers at least one highly unsaturated polymerhaving an iodine number of between about 100 and
 400. 10. A tireaccording to claim 9, wherein said one highly unsaturated polymer isselected from the group consisting of natural rubber, cis-polyisoprene,polybutadiene and poly(styrene-butadiene).
 11. A tire according to claim10 further comprising an elastomer having lesser unsaturation than saidhighly unsaturated polymer, said elastomer being selected from the groupconsisting of EPDM, EPR, butyl rubber and halogenated butyl rubber. 12.A tire according to claim 10, wherein said antidegradant compositionfurther comprises an effective amount of at least oneparaphenylenediamine antiozonant.
 13. A tire according to claim 12,wherein the amount of compound of structure (I) is between 0:1 to about10 parts by weight per one hundred parts by weight of said thermosettingrubber, and the ratio of paraphenylenediamine antiozonant to thecompound of structure (I) is from 1:3 to 3:1.
 14. A tire according toclaim 13, wherein said compound of structure (I) is added at levels ofabout 1 to about 6 parts by weight per one hundred parts of saidthermosetting rubber polymers.
 15. A tire according to claim 12, whereinsaid antidegradant composition is present at a level of 1 to 6 parts byweight per one hundred parts by weight of said thermosetting rubberpolymers.
 16. A tire according to claim 15, wherein saidparaphenylenediamine and said compound of a structure (I) are present insaid antidegradant composition in a ratio from 1:3 to 3:1.
 17. A tireaccording to claim 6 wherein said elastomers having lesser unsaturationis an ethylene-propylene-diene rubber having an ethylene to propyleneweight ratio of about 50:50 to about 75:25 and having about 2 to about20 weight percent non-conjugated diene based on total weight of saidEPDM rubber.
 18. A tire according to claim 17 wherein saidethylene-propylene-diene rubber is an admixture withN-chlorothiosulfonamide.
 19. A tire according to claim 18 wherein saidnon-conjugated diene in said ethylene-propylene-diene rubber isethylidene norbornene at about 2 to about 20 weight percent of totalethylene-propylene-diene rubber.
 20. A tire according to claim 17wherein said ethylene-propylene-diene rubber is of high molecular weightand extended with between 50 and 150 parts by wight of oil per 100 partsof rubber.